Group-iii nitride device and preparation method thereof

Abstract

The disclosure provides a group-III nitride device. The group-III nitride device includes a heterojunction epitaxial wafer and at least one island-shaped electrode. The at least one island-shaped electrode of the group-III nitride device is disposed on the heterojunction epitaxial wafer. Each of the at least one island-shaped electrode includes an interconnection metal layer and at least one island-shaped structural layer. The island-shaped structural layer is covered by the interconnection metal layer and connected to the interconnection metal layer.

What is claimed is: 
     
         1 . A group-III nitride device, comprising:
 a heterojunction epitaxial wafer; and   at least one island-shaped electrode disposed on the heterojunction epitaxial wafer, wherein each of the at least one island-shaped electrode comprises an interconnection metal layer and at least one island-shaped structural layer, wherein the at least one island-shaped structural layer is covered by the interconnection metal layer and connected to the interconnection metal layer.   
     
     
         2 . The group-III nitride device according to  claim 1 , wherein a depletion region of the at least one island-shaped electrode under a bias condition is expanded to a region around the at least one island-shaped electrode. 
     
     
         3 . The group-III nitride device according to  claim 1 , wherein after the heterojunction epitaxial wafer is downwardly etched, at least one hole-shaped groove is formed, and each of the at least one island-shaped structural layer is formed in the corresponding hole-shaped groove. 
     
     
         4 . The group-III nitride device according to  claim 3 , wherein a depth of the hole-shaped groove is ranged between 60 nm and 100 nm. 
     
     
         5 . The group-III nitride device according to  claim 3 , wherein a thickness of the island-shaped structure layer is ranged between 80 nm and 120 nm, and the island-shaped structure layer and the heterojunction epitaxial wafer are contacted with each other in the hole-shaped groove. 
     
     
         6 . The group-III nitride device according to  claim 1 , wherein the island-shaped structure layer is made of a metallic material, a semiconductor material, or a combination thereof. 
     
     
         7 . The group-III nitride device according to  claim 1 , wherein the interconnection metal layer is made of nickel, gold, palladium, platinum, titanium, titanium nitride, conductive glass, or a combination thereof. 
     
     
         8 . The group-III nitride device according to  claim 1 , wherein the group-III nitride device is a photodetector and the at least one island-shaped electrode is served as a positive electrode or a negative electrode of the photodetector. 
     
     
         9 . The group-III nitride device according to  claim 8 , wherein the interconnection metal layer is a translucent interconnection metal layer. 
     
     
         10 . The group-III nitride device according to  claim 9 , wherein a thickness of the translucent interconnection metal layer is ranged between 5 nm and 10 nm. 
     
     
         11 . The group-III nitride device according to  claim 1 , wherein the group-III nitride device is a high electron mobility transistor and the at least one island-shaped electrode is served as a gate electrode of the high electron mobility transistor. 
     
     
         12 . The group-III nitride device according to  claim 1 , wherein the group-III nitride device is a lateral field effect rectifier and the at least one island-shaped electrode is served as an anode electrode of the lateral field effect rectifier. 
     
     
         13 . A preparation method of a group-III nitride device, the preparation method comprising steps of:
 (S1) providing a heterojunction epitaxial wafer;   (S2) defining an island-shaped structure layer region on the heterojunction epitaxial wafer, and performing an etching process to form a hole-shaped groove in the heterojunction epitaxial wafer corresponding to the island-shaped structure layer region;   (S3) forming an island-shaped structure layer in the hole-shaped groove; and   (S4) defining an interconnection metal layer region and forming an interconnection metal layer on the interconnection metal layer region, wherein the island-shaped structural layer is covered by the interconnection metal layer and connected to the interconnection metal layer.   
     
     
         14 . The preparation method according to  claim 13 , the island-shaped structural layer and the interconnection metal layer are collaboratively formed as at least one island-shaped electrode. 
     
     
         15 . The preparation method according to  claim 13 , wherein in the step (S2), the etching process is an inductively coupled plasma reactive ion etching process. 
     
     
         16 . The preparation method according to  claim 15 , wherein the heterojunction epitaxial wafer comprises a substrate, a buffer layer, a channel layer and a barrier layer from bottom to top, wherein in the step (S2), the hole-shaped groove is formed after a portion of the barrier layer and a portion of the channel layer corresponding to the island-shaped structure layer region are etched. 
     
     
         17 . The preparation method according to  claim 13 , wherein in the step (S3), an electron beam evaporation deposition process is performed to deposit a material of the island-shaped structure layer in the hole-shaped groove, so that the island-shaped structure layer is formed. 
     
     
         18 . The preparation method according to  claim 13 , wherein in the step (S4), an electron beam evaporation deposition process is performed to deposit a material of the interconnection metal layer on the interconnection metal layer region, so that the interconnection metal layer is formed.